KR101846039B1 - Membrane electrode assembly, method for producing membrane electrode assembly, and fuel battery - Google Patents

Abstract

The present invention relates to a membrane electrode assembly which has high adhesion strength at the interface between the polymer electrolyte membrane and the catalyst layer and which is difficult to peel off the catalyst layer from the polymer electrolyte membrane and a method for producing the membrane electrode assembly, And to provide a fuel cell.
In the method for producing the membrane electrode assembly 4, since the ink including the solvent is directly applied to the adjacent layer to form the adhesive layer 2 and the catalyst layer 3, the polymer electrolyte at the interface is slightly dissolved and adhered. This makes it possible to increase the bonding strength between the polymer electrolyte membrane 1 and the catalyst layer 3 at the interface with each other as compared with the method of separately thermally bonding the adhesive layer and the catalyst layer provided on the substrate. In addition, the membrane electrode assembly 4 has high adhesion strength at the interface between the polymer electrolyte membrane 1 and the catalyst layer 3, and the catalyst layer 3 is difficult to peel off from the polymer electrolyte membrane 1. In addition, the fuel cell using the membrane electrode assembly 4 has excellent cell performance because the catalyst layer 3 is difficult to peel off from the polymer electrolyte membrane 1.

Description

TECHNICAL FIELD [0001] The present invention relates to a membrane electrode assembly, a membrane electrode assembly,

The present invention relates to a membrane electrode assembly, a method of manufacturing a membrane electrode assembly, and a fuel cell including the membrane electrode assembly.

In order to improve the cell performance of the membrane electrode assembly used in the fuel cell, it is important that the adhesion between the polymer electrolyte membrane and the catalyst layer is high. Therefore, if the adhesion strength between the polymer electrolyte membrane and the catalyst layer is weak, the catalyst layer may peel off from the polymer electrolyte membrane, thereby deteriorating battery performance. In particular, in the case of using a hydrocarbon-based polymer electrolyte membrane, there is a high possibility that the cell performance is deteriorated because the adhesion strength between the polymer electrolyte membrane and the catalyst layer is weak.

In order to increase the bonding strength, a method of providing an adhesive layer containing a polymer electrolyte having a proton conductivity between a polymer electrolyte membrane and a catalyst layer is known. As such a method, Patent Documents 1 and 2 disclose a method for producing a membrane electrode assembly in which an adhesive layer containing a proton conductive polymer electrolyte is formed on one of a polymer electrolyte membrane or a catalyst layer, followed by thermocompression bonding the both.

Japanese Patent No. 3608565 Japanese Patent Application Laid-Open No. 2009-231123

However, in the production method of joining the adhesive layer and the catalyst layer by thermocompression bonding, the bonding strength between the interface between the polymer electrolyte membrane and the catalyst layer is not sufficient, and there is a fear that both are peeled off during power generation of the fuel cell.

An object of the present invention is to provide a membrane electrode assembly which has a high adhesion strength at the interface between the polymer electrolyte membrane and the catalyst layer and which is difficult to peel off the catalyst layer from the polymer electrolyte membrane, and a method for producing the membrane electrode assembly.

According to an aspect of the present invention, there is provided a method of manufacturing a membrane electrode assembly according to one aspect of the present invention, the method including: forming a polymer electrolyte membrane, a catalyst layer disposed on both surfaces of the polymer electrolyte membrane, Wherein the adhesive layer and the catalyst layer are formed by a coating method when the membrane electrode assembly including the polymer electrolyte membrane and the adhesive layer for bonding the catalyst layer is formed by sequentially laminating the adhesive layer and the catalyst layer on the polymer electrolyte membrane .

The manufacturing method of the membrane electrode assembly may further comprise: a fixing step of fixing the polymer electrolyte membrane; a heating step of heating the polymer electrolyte membrane fixed in the fixing step; and a step of heating the polymer electrolyte membrane, A first forming step of forming an adhesive layer by applying an adhesive layer ink containing an electrolyte and a solvent, and drying the coated layer; and a step of applying a catalyst layer ink containing a catalyst material and a solvent on the adhesive layer, 2 forming process.

The heating temperature of the polymer electrolyte membrane in the heating step is preferably 60 ° C or higher and 200 ° C or lower.

Further, the membrane electrode assembly according to an embodiment of the present invention is characterized by being manufactured by the above-described method of manufacturing a membrane electrode assembly.

Further, a fuel cell according to an aspect of the present invention is characterized by including the membrane electrode assembly described above.

In the method for producing a membrane electrode assembly of the present invention, an ink containing a solvent is directly applied to an adjacent layer to form an adhesive layer and a catalyst layer, so that the polymer electrolyte at the interface is slightly dissolved and adhered. Therefore, the bonding strength between the polymer electrolyte membrane and the catalyst layer at the interface can be increased, as compared with the manufacturing method in which the adhesive layer and the catalyst layer separately provided on the substrate are thermocompression bonded. In addition, since the thermocompression bonding step is not required, the number of manufacturing steps can be reduced.

In addition, since the method for manufacturing a membrane electrode assembly of the present invention includes a step of fixing and heating the polymer electrolyte membrane, even when the adhesive layer ink and the catalyst layer ink are applied directly, the solvent can be immediately evaporated and removed, It is possible to suppress the deformation of the polymer electrolyte membrane caused by the polymer electrolyte membrane.

In addition, the membrane electrode assembly of the present invention has high adhesion strength to the interface between the polymer electrolyte membrane and the catalyst layer, and the catalyst layer is difficult to peel off from the polymer electrolyte membrane. In addition, the fuel cell using the membrane electrode assembly of the present invention has excellent cell performance because the interface strength between the polymer electrolyte membrane and the catalyst layer is high and the catalyst layer is difficult to peel off from the polymer electrolyte membrane.

1 is a schematic cross-sectional view of a membrane electrode assembly according to an embodiment of the present invention.
2 is a schematic cross-sectional view of another membrane electrode assembly according to the present embodiment.
3 is an explanatory diagram of a method for producing a membrane electrode assembly according to the present embodiment.

Embodiments of the present invention will be described below.

1 is a schematic cross-sectional view of a membrane electrode assembly 4 of the present embodiment.

The membrane electrode assembly 4 shown in Fig. 1 has an adhesive layer 2 laminated on both surfaces of a polymer electrolyte membrane 1 and a surface opposite to a surface on which the polymer electrolyte membrane 1 of the adhesive layer 2 is laminated And a catalyst layer 3 stacked on the catalyst layer 3.

The adhesive layer 2 is formed by applying an adhesive layer ink to be described later to the polymer electrolyte membrane 1 and drying it, and contains a proton-conducting polymer electrolyte. The thickness of the adhesive layer 2 preferably has such a thickness as to maintain the bonding strength between the polymer electrolyte membrane 1 and the catalyst layer 3 and preferably has a thickness of 0.1 to 3 m . If the thickness is less than 0.1 탆, there is a possibility that sufficient adhesive strength can not be maintained. If the thickness exceeds 3 m, the resistance of the adhesive layer 2 is increased, and therefore there is a fear that the cell performance of the fuel cell using the membrane electrode assembly 4 is lowered.

The catalyst layer 3 contains a catalyst and a polymer electrolyte. The catalyst layer 3 is formed by applying catalyst layer ink described later to the adhesive layer 2 and then drying it.

The polymer electrolyte contained in the polymer electrolyte membrane 1, the adhesive layer 2 and the catalyst layer 3 is not particularly limited as long as it has proton conductivity. For example, a fluorinated polymer electrolyte, a hydrocarbon-based polymer electrolyte, or the like can be used. The same type of polymer electrolyte may be used for the polymer electrolyte membrane 1, the adhesive layer 2 and the catalyst layer 3, or a different kind of polymer electrolyte may be used.

As the fluorinated polymer electrolyte, for example, Nafion (registered trademark) manufactured by Du Pont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Kasei Kabushiki Kaisha And Gore Select (registered trademark) manufactured by Gore & Co., Ltd. can be used.

As the hydrocarbon-based polymer electrolyte, an electrolyte such as a sulfonated polyether ketone, a sulfonated polyether sulfone, a sulfonated polyether ether sulfone, a sulfonated polysulfide, or a sulfonated polyphenylene can be used.

As the polymer electrolyte membrane 1, a membrane containing the above-described polymer electrolyte can be used. The polymer electrolyte contained in the adhesive layer 2 is preferably highly adhesive to the polymer electrolyte membrane 1 and the polymer electrolyte contained in the catalyst layer 3. For example, the polymer electrolyte membrane 1 and the catalyst layer 3 And a polymer electrolyte having a softening temperature lower than that of the polymer electrolyte contained in the polymer electrolyte membrane (3). Specifically, a polymer electrolyte having a softening temperature lower by 0 ° C to 200 ° C than the polymer electrolyte contained in the polymer electrolyte membrane (1) and the catalyst layer (3) is used. This makes it easier for the polymer electrolyte contained in the adhesive layer 2 to be softened by heat than the polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 3, The interface can be bonded. The softening temperature of the polymer electrolyte can be determined as the peak temperature of tan delta obtained by performing dynamic viscoelasticity measurement while raising the temperature to about 4 DEG C / min.

The adhesive layer ink contains a polymer electrolyte and a solvent. Further, the catalyst layer ink contains a catalyst material and a solvent.

The solvent contained in the adhesive layer ink and the catalyst layer ink is not particularly limited as long as it is a solvent for dispersing the polymer electrolyte, but is preferably a solvent which is easily removed by evaporation by heating. For example, the solvent is preferably a solvent having a boiling point of 150 ° C or lower. Further, the solvent may be evaporated by heating under reduced pressure or an air flow. Further, the solvent may be removed only by introducing a reduced pressure or an air stream without heating. Specific examples of the solvent include water, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol and pentanol, , Ketones such as methyl isobutyl ketone, heptanone, cyclohexanone, methylcyclohexanone, acetonyl acetone and diisobutyl ketone, ketones such as tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, anisole, methoxy toluene, 1-methoxy-2-propanol, and the like, and other solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol, diacetone alcohol, Or more may be used.

As the catalyst, for example, a catalyst material supported on conductive particles such as carbon particles can be used. Examples of the catalytic material include metals such as iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium and aluminum as well as palladium, ruthenium, iridium, rhodium and osmium of the platinum group elements, Or oxides, double oxides and the like. The kind of the carbon particles is not particularly limited as long as it is in the form of fine particles and has conductivity and can not be changed by the catalyst, but carbon black, graphite, graphite, activated carbon, carbon fiber, carbon nanotube and fullerene can be used.

When the particle size of the carbon particles is too small, it is difficult to form the electron conduction path. On the other hand, if it is too large, gas diffusion property of the catalyst layer may be lowered, but utilization of the catalyst may be lowered. Therefore, the particle diameter of the carbon particles is preferably from about 10 nm to about 1000 nm, more preferably from about 10 nm to about 100 nm. The solvent of the catalyst layer ink is preferably a solvent capable of dissolving or dispersing the polymer electrolyte and the catalytic material, but it is preferable that the solvent is easily evaporated by heating in the same manner as the solvent contained in the adhesive layer ink. For example, the solvent is preferably a solvent having a boiling point of 150 ° C or lower.

3 is an explanatory diagram of a method of manufacturing the membrane electrode assembly of the present embodiment.

The method for producing a membrane electrode assembly according to the present embodiment is characterized in that the adhesive layer 2 and the catalyst layer 3 are formed directly by applying the adhesive layer ink and the catalyst layer ink successively while heating and fixing the polymer electrolyte membrane 1 .

First, the polymer electrolyte membrane 1 is fixed to the fixing means 5. The fixing means 5 is preferably a means capable of fixing the polymer electrolyte membrane 1 so as not to move and twist while applying the adhesive layer ink and the catalyst layer ink to the polymer electrolyte membrane 1. [ Specifically, in the method of fixing only a part of the end portion or the like of the polymer electrolyte membrane 1, since the polymer electrolyte membrane 1 may move during the application of the respective inks, the entire polymer electrolyte membrane 1 is fixed . Examples of the fixing means 5 for fixing the polymer electrolyte membrane 1 include a porous plate provided with a suction mechanism by reduced pressure, a sticky plate, and a plate attracted by static electricity. In the case of using a porous plate, the polymer electrolyte membrane 1 can be fixed by being adsorbed under reduced pressure from the surface opposite to the surface on which the polymer electrolyte membrane 1 is disposed.

Then, the fixed polymer electrolyte membrane 1 is heated by the heating means 6. The heating means 6 is not particularly limited as long as it can heat the fixed polymer electrolyte membrane 1. Examples of the heating means 6 include a heating device such as an oven or heater provided adjacent to the fixing means 5, an apparatus for controlling the temperature in the vicinity of the polymer electrolyte membrane 1 by using infrared rays, . In addition, heat may be conducted to the polymer electrolyte membrane 1 through the fixing means 5. The temperature range of heating is preferably close to the boiling point of the solvent and not higher than the glass transition temperature of the polymer electrolyte membrane 1. [ Specifically, when the above-described polymer electrolyte is used, it is preferable that the temperature is in the range of 60 ° C or more and 200 ° C or less.

Subsequently, an adhesive layer ink is applied to the fixed, heated polyelectrolyte membrane 1 and then dried to form the adhesive layer 2. [ The adhesive layer 2 can be formed by heating the coating film 2a of the adhesive layer ink and evaporating the solvent.

Subsequently, the catalyst layer ink is coated on the adhesive layer 2 and then dried to form the catalyst layer 3. [ The catalyst layer 3 can be formed by heating the coating film 3a of the catalyst layer ink and evaporating the solvent. The polymer electrolyte membrane 1 and the adhesive layer 2 are heated by the heating means 6 before the catalyst layer ink is applied to the adhesive layer 2 in order to suppress deformation and wrinkling of the polymer electrolyte membrane 1 It may be fixed by fixing means 5 after heating.

The membrane electrode assembly 4 can be produced by forming the adhesive layer 2 and the catalyst layer 3 on the other surface of the polymer electrolyte membrane 1 by the same procedure.

The method of applying the adhesive layer ink and the catalyst layer ink is not particularly limited as long as it is a method capable of coating in a desired shape, and for example, a die coating method, a screen printing method, a spray method, or the like can be used.

2 is a schematic cross-sectional view of another membrane electrode assembly 4 of the present embodiment.

The adhesive layer 2 ink and the catalyst layer ink are directly applied to the adjacent layers to form the adhesive layer 2 and the catalyst layer 3 respectively so that the polymer electrolyte at the interface is slightly dissolved and the adhesion between the polymer electrolyte membrane 1 and the adhesive layer 2, (7) in which the polymer electrolyte of each layer is mixed is formed between the catalyst layer (2) and the catalyst layer (3). The formation of the mixed layer 7 can be carried out by selecting the softening temperature of the polymer electrolyte contained in the adhesive layer ink or the catalyst layer ink, the type of the solvent contained in the adhesive layer ink or the catalyst layer ink, the heating temperature in the heating process of the polyelectrolyte membrane 1, Or drying conditions at the time of drying after application of the catalyst layer ink.

The mixed layer 7 between the polyelectrolyte membrane 1 and the adhesive layer 2 and the mixed layer 7 between the adhesive layer 2 and the catalyst layer 3 are formed by the polymer electrolyte membrane 1, Depending on the combination of the polymer electrolyte contained in the catalyst layer 3, a mixed layer of different composition may be obtained.

According to the manufacturing method of the membrane electrode assembly 4 of the present embodiment, since the adhesive layer ink including the solvent and the catalyst layer ink are in contact with the adjacent layer, the polymer electrolyte at the interface is slightly dissolved and adhered. Therefore, the bonding strength between the interface between the polymer electrolyte membrane 1 and the adhesive layer 2, and the interface between the adhesive layer 2 and the catalyst layer 3 can be increased. Further, since the thermocompression bonding step is not required, the number of manufacturing steps can be reduced as compared with the method of thermocompression bonding the adhesive layer and the catalyst layer separately provided on the substrate.

In addition, since the solvent contained in the adhesive layer ink and the catalyst layer ink often tends to swell the polymer electrolyte membrane, there is a case where the solvent is deformed and wrinkles are generated upon contact with the polymer electrolyte membrane. In the manufacturing method of the present embodiment, 6 to remove the solvent by evaporation, so that deformation and wrinkling of the polymer electrolyte membrane 1 can be suppressed.

The membrane electrode assembly 4 of the present embodiment has a high bonding strength to the interface between the polymer electrolyte membrane 1 and the catalyst layer 3 and is difficult to peel off the catalyst layer 3 from the polymer electrolyte membrane 1. The fuel cell using the membrane electrode assembly 4 of the present embodiment has a high adhesion strength at the interface between the polymer electrolyte membrane 1 and the catalyst layer 3 and the peeling of the catalyst layer 3 from the polymer electrolyte membrane 1 It has excellent cell performance.

Example

[Production of adhesive layer ink]

20% by mass of a polymer electrolyte solution (Nafion 占 manufactured by DuPont) was diluted with ethanol and stirred to prepare an adhesive layer ink.

[Preparation of catalyst layer ink]

A 20 mass% polyelectrolyte solution (Nafion (registered trademark) manufactured by DuPont) was mixed with a mixed solvent of water and ethanol, and a mixture of a platinum supported carbon catalyst (TEC10E50E (trade name), manufactured by Tanaka Kikinzoku Kogyo K.K.) And dispersed with a planetary ball mill to prepare a catalyst layer ink.

[Example 1]

A polymer electrolyte membrane using a sulfonated polyether ketone as a polymer electrolyte was used. The polymer electrolyte membrane was placed on one side of a porous plate having an adsorption mechanism, and adsorbed and fixed. A heater was disposed on the other surface of the porous plate, and the temperature of the polymer electrolyte membrane was set to be 80 캜. An adhesive layer ink was applied on the polymer electrolyte membrane by a screen printing method and the solvent was evaporated to form an adhesive layer on the polymer electrolyte membrane. Subsequently, the catalyst layer ink was applied on the adhesive layer by screen printing to evaporate the solvent to form a catalyst layer on the adhesive layer. The above operation was performed on both sides of the polymer electrolyte membrane to prepare a membrane electrode assembly.

[Comparative Example 1]

A polymer electrolyte membrane using a sulfonated polyether ketone as a polymer electrolyte was used. The adhesive layer ink and the catalyst layer ink were respectively coated on the substrate of the polymer film and dried to prepare an adhesive layer and a catalyst layer. A polytetrafluoroethylene (PTFE) film was used as a base material of the polymer film. The polymer electrolyte membrane and the adhesive layer formed on the substrate were bonded to each other, and the resultant was heated and pressed for 10 minutes using a hot press apparatus set at 180 占 폚 to join the interfaces and peel the base material to place the adhesive layer on the polymer electrolyte membrane Respectively. Subsequently, the catalyst layer formed on the substrate was bonded to the adhesive layer, and the catalyst layer was placed on the adhesive layer by bonding the interfaces by heating and pressing for 10 minutes using a hot press apparatus set at 180 DEG C, Respectively. An adhesive layer and a catalyst layer were disposed on both sides of the polymer electrolyte membrane to prepare a membrane electrode assembly.

The membrane electrode assemblies manufactured by the manufacturing method of Example 1 and Comparative Example 1 were evaluated for adhesion strength by a peeling test using a cellophane tape (registered trademark). In the peeling test, the adhesive strength between the catalyst layer and the polymer electrolyte membrane is evaluated by attaching a cellophane tape (registered trademark) to the catalyst layer and peeling the cellophane tape (registered trademark).

When the cellophane tape (registered trademark) was attached to the catalyst layer of the membrane electrode assembly of Comparative Example 1 and the cellophane tape (registered trademark) was peeled off, the catalyst layer was easily peeled together with the cellophane tape (registered trademark), and the interface between the polymer electrolyte membrane and the adhesive layer , The adhesive strength between the adhesive layer and the catalyst layer at the interface was insufficient.

On the other hand, when the cellophane tape (registered trademark) was attached to the catalyst layer of the membrane electrode assembly of Example 1 and the cellophane tape (registered trademark) was peeled off, the catalyst layer was hardly peeled off from the polymer electrolyte. Further, the electrical resistance of the fuel cell using the membrane electrode assembly of Example 1 at the time of power generation was lower than that of Comparative Example 1. From this, it is considered that the bonding strength between the interface between the polymer electrolyte membrane and the adhesive layer and the interface between the adhesive layer and the catalyst layer is high.

Since the membrane electrode assembly of the present invention has a high bonding strength at the interface, there is little problem of long-term durability when it is used in a solid polymer type fuel cell. Therefore, the present invention can be suitably used for a fuel cell using a polymer electrolyte membrane, particularly a static type cogeneration system or a fuel cell automobile.

1 Polymer electrolyte membrane
2 adhesive layer
2a coating film of the adhesive layer ink
3 catalyst layer
3a Coating layer of catalyst layer ink
4 membrane electrode assembly
5 fixing means
6 Heating means
7 mixed layer

Claims (7)

A polymer electrolyte membrane,
A catalyst layer disposed on both sides of the polymer electrolyte membrane,
A membrane electrode assembly disposed between the polymer electrolyte membrane and the catalyst layer and having an adhesive layer for bonding the polymer electrolyte membrane and the catalyst layer,
When the adhesive layer and the catalyst layer are sequentially laminated on the polymer electrolyte membrane,
Wherein the adhesive layer and the catalyst layer are formed by a coating method,
A fixing step of fixing the polymer electrolyte membrane,
A heating step of heating the polymer electrolyte membrane fixed in the fixing step,
A first forming step of applying an adhesive layer ink containing a polymer electrolyte and a solvent on the polymer electrolyte membrane heated in the heating step and then drying the resultant to form the adhesive layer;
A second forming step of forming a catalyst layer by applying a catalyst layer ink containing a catalyst material and a solvent on the adhesive layer,
And forming a membrane electrode assembly on the membrane electrode assembly. delete The method for manufacturing a membrane-electrode assembly according to claim 1, wherein the heating temperature of the polymer electrolyte membrane in the heating step is 60 占 폚 or more and 200 占 폚 or less. A polymer electrolyte membrane,
A catalyst layer disposed on both sides of the polymer electrolyte membrane,
A membrane electrode assembly disposed between the polymer electrolyte membrane and the catalyst layer, the membrane electrode assembly comprising an adhesive layer for bonding the polymer electrolyte membrane and the catalyst layer,
And a first mixed layer formed between the polymer electrolyte membrane and the adhesive layer and including a first polymer electrolyte contained in the polymer electrolyte membrane and a second polymer electrolyte included in the adhesive layer,
And a second mixed layer in which the second polymer electrolyte and a third polymer electrolyte contained in the catalyst layer are mixed between the adhesive layer and the catalyst layer,
Wherein the second polymer electrolyte comprises a polymer electrolyte having a lower softening temperature than the first polymer electrolyte and the third polymer electrolyte. The membrane electrode assembly according to claim 4, wherein the first polymer electrolyte and the third polymer electrolyte include the same type of polymer electrolyte. 5. The membrane electrode assembly of claim 4, wherein the first polymer electrolyte and the third polymer electrolyte comprise different kinds of polymer electrolytes. A fuel cell comprising the membrane electrode assembly according to any one of claims 4 to 6.

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